[gs-bugs] [Bug 692588] Some watermarked PDF files are rasterized when converting to PDF/A - #1524

bugzilla-daemon at ghostscript.com bugzilla-daemon at ghostscript.com
Thu Oct 13 13:21:18 UTC 2011


http://bugs.ghostscript.com/show_bug.cgi?id=692588

Ken Sharp <ken.sharp at artifex.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID

--- Comment #7 from Ken Sharp <ken.sharp at artifex.com> 2011-10-13 13:21:17 UTC ---
(In reply to comment #6)

> Other files that contain images do convert to PDF/A just fine. How can I find
> out why this one (see attachment) does not? Interestingly when I specify
> "-DNOTRANSPARENCY" the problem goes away and the image is still visible.

That means the input contains transparency. It may not do anything useful, but
the code can't tell that, it contains transparency so we assume it will have
some effect and treat it accordingly.

NB I haven't actually looked at the file, but this is what must be happening.


> This same switch solves the problem with the other file as well
> (Source-Form.pdf) and the resulting PDF/A file looks identical to the source
> file. 

Same problem then.


> So if there is no list readily available of elements that cause a page to be
> rasterised, 

There are no elements which will cause a page to be rasterised, but the
presence of transparency will, because the specification doesn't permit
transparency.

>is there some kind of diagnostics output I can enable this so I can
> run tests on documents that don't behave as expected.

Hmm, I don't think so, no. Transparency in PDF documents is unfortunately
complicated, the elements can appear in all sorts of places and there is no
overriding 'this document contains transparency' in the PDF file. 

Ah, the pdf_info.ps file supplied as part of Ghostscript will tell you if a
given page uses transparency. This tool reports that both your files use
transparency.

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